The most common cause that prevents a user from playing WMV files in Windows Media Player is an inability of the program to handle files that contain multiple video streams. If the streams are meant to be played at once, Windows Media Player 11 reports a problem because it can only reproduce one video stream at a time. Alternatively, the problem could results from not having the correct codecs installed.
The problem involving multiple video streams can be fixed by downloading the relevant hotfix from the Microsoft website. Once the hotfix has been applied, Windows Media Player 11 gains the ability to detect the number of video streams, and it uses Windows Media Format SDK to reproduce the video file instead of Media Foundation, which causes the problem initially.
The problem involving codecs can be rectified by configuring the Windows Media Player 11 to download the codecs automatically. This is done by opening the Tools menu, clicking on Options and then checking the “Download codecs automatically” box located under the Player tab. If this doesn’t solve the problem, a user can right-click on the file and analyze the codec properties. Once the appropriate codecs have been determined, download them from websites that provide third-party codecs.